Self discipline is fixing that tricky system outage that takes out production at midnight and requires great concentration, even though the early waking sysops give up and bow-out of the conference call because they "can't think straight" leaving those late waking engineers to pick up the pieces.

If you "get your ass out of bed" when you are actually rested, that shows that you value the quality of the work you do during the day, a valued trait.

People who get up early are just lazy night-work shirkers who could possibly be deadly to the companies servers.